There were 20,925 households out of which 32.10% had children under the age of 18 living with them, 53.70% were married couples living together, 12.90% had a female householder with no husband present, and 28.70% were non-families. 23.80% of all households were made up of individuals and 9.80% had someone living alone who was 65 years of age or older. The average household size was 2.56 and the average family size was 3.02.

In the county the population was spread out with 25.40% under the age of 18, 9.00% from 18 to 24, 27.70% from 25 to 44, 24.00% from 45 to 64, and 14.00% who were 65 years of age or older. The median age was 37 years. For every 100 females there were 102.90 males. For every 100 females age 18 and over, there were 101.70 males.

The median income for a household in the county was $30,881, and the median income for a family was $35,927. Males had a median income of $27,353 versus $21,738 for females. The per capita income for the county was $14,598. About 11.40% of families and 15.00% of the population were below the poverty line, including 17.10% of those under age 18 and 13.60% of those age 65 or over.

Interstate 10 is the main west-to-east interstate highway in the county, and serves as the unofficial dividing line between northern and southern Columbia County. It contains three interchanges within the state; the first being I-75 in Springville (Exits 296 A-B), and the other two in Five Points, north of Lake City, US 41 (Exit 301), and US 441(Exit 303). Beyond this point I-10 runs through Osceola National Forest.

Interstate 75 is the southwest-to-northeast interstate highway in the county, which enters from Alachua County at bridges over the Santa Fe River. It has four interchanges in the county with US 41/441 in Ellisville (Exit 414), SR 47 (Exit 423), US 90 in Lake City (Exit 427) and I-10 in Springville (Exits 435 A-B).

US 41 runs north from High Springs in a concurrency with US 441 until just before it reaches Lake City, Then the two routes run parallel to each other until US 41 branches off to the northwest on its way to Hamilton County, Valdosta, Georgia, and points north.

US 90 was the main west-to-east highway in the county, until it was surpassed by I-10. It enters the county from Wellborn in Suwannee County, and directly enters Lake City. East of the city, it runs along the southern edge of Osceola National Forest and serves as the address of two major prisons before crossing the Baker County Line and entering a portion of the forest itself.

US 441 runs north from High Springs in a concurrency with US 41 until just before it reaches Lake City, Then the two routes run parallel to each other, but unlike US 41, US 441 stays in Columbia County and runs straight north and south until it crosses the Georgia State Line.

State Road 2 is located on the far northeast corner of the county, and has no intersections whatsoever.

State Road 47 is a northeast-to-southwest road that spans from Trenton in Gilchrist County to US 41 in Lake City. North of there it becomes a hidden state road along US 41 until it reaches US Truck Route 90, then turns east, only to turn north again onto US 441 where it remains for the duration until it crosses the Florida-Georgia State Line.